1. Field of the Invention
The present invention relates to a constant velocity universal joint used in a car and an industrial machinery and a method of controlling the quality thereof with the use of an IC tag.
2. Description of Prior Art
In recent years, demands for the traceability of an object of interest, that is, demands for the capability of pursuing the history, application and/or whereabouts of an object of interest are increasing. In the quality control of mechanical products, for example, constant velocity universal joints, the quality of every steps (material purchase step, forging step, heat treatment step, grinding step and so on) of the manufacturing process ranging from material purchase to completion of manufacture and the manufacturing history of, for example, lots are desired to be confirmed on one-to-one basis or by unit of lots for each of the mechanical products.
In automotive vehicles, since general mechanical products are controlled in lot units and lot-by-lot sampling inspection procedure is carried out for each lot, the manufacturing history in lot units is required. Once the manufacturing history is known, countermeasures to the future's improvements can be eased and the diagnosis of the service line can also be conducted easily. Also, determination of contamination of analogous articles can be facilitated. In the case of specialty mechanical products, individual examination is carried out and the manufacturing history is desired to be discernable on a one-by-one basis.
As a quality control method capable of clarifying such a manufacturing history, information generated during each manufacturing step has hitherto been recorded in forms and/or inputted to a terminal for a database.
On the other hand, in the distribution control and/or the stock control, IC tags adopting the FRID capable of contactless communication are being compactized and come to be largely employed in the distribution of goods. In the manufacture of a product of, for example, an automotive vehicle, the control from the stage of manufacture to the stage of disposal with the use of the IC tags has been suggested. (See, for example, the Japanese Laid-open Patent Publication No. 2002-169858.) Since the IC tag is capable of achieving a contactless communication and has a large storage capacity, a high degree control is expected. Even in mechanical elements such as gears, it has been suggested to attach the IC tags to the product and store therein ID codes and various information associated with the ID codes so that information on the products can be controlled. (See, for example, the Japanese Laid-open Patent Publication No. 2002-49900.)
However, with respect to the constant velocity universal joints, an example, in which the IC tag is attached, has not yet been suggested. Also, if an attempt is made to attach the IC tag to the constant velocity universal joint, it is necessary to avoid the IC tag from disturbing the peripheral arrangement, to avoid interference of the IC tag with the peripheral arrangement and to avoid an accidental separation of the IC tag during the use thereof for a long time. The standard IC tags are often incapable of accomplishing a satisfactory information recording, when they are arranged on metals, due to radio wave absorption and radio wave reflection. If the IC tags of a special construction capable of being arranged on metals are used, they will become expensive, which lead to increase of the cost of the constant velocity universal joints.
The conventional control of mechanical elements with the use of the IC tags deals with the control of information obtained at manufacturing stages and the control of information concerning the product distribution, and no suggestion has been made yet to control the status of actual use of the mechanical elements subsequent to shipment.
The constant velocity universal joint utilized in association with, for example, a drive shaft of an automotive vehicle is generally designed to have a service life corresponding to the life of the automotive vehicle. Accordingly, if one can ascertain how it is used in the market, it will be useful as information for the future's designing.
However, no clue is generally available, which is necessary to know how the constant velocity universal joint is used and, therefore, confirmation of the actual use thereof in a particular status is impossible to achieve. Although an attempt is made to store and control the status-of-use of the automotive vehicle itself, it is not sufficient as information necessary to control the status-of-use of the constant velocity universal joint. Also, in the event that the constant velocity universal joint is replaced with a fresh one in the automotive vehicle, it is not easy to know the status-of-use of the new constant velocity universal joint.
When it comes to the regular servicing of the constant velocity universal joint that takes place during an automobile inspection or the like, it often occurs that indications of the manufacturer's serial number, and/or the date of manufacture and the place of manufacture, imprinted on the constant velocity universal joint are necessary.
However, the indications such as the manufacturer's serial number, the date of manufacture and the place of manufacture, which are imprinted on the constant velocity universal joint, are not readily available unless the constant velocity universal joint is dismantled. Because of this, disassembling and reassembling require a substantial amount of labors. In general, the constant velocity universal joint must be removed to enable the information such as the manufacturer's serial number to be confirmed and this is indeed laborious and costly.
In the suggested example of the quality control method using the IC tags, various pieces of information concerning mechanical elements, for example, gears, are recorded directly in the IC tag attached to each of the mechanical elements or identification information is recorded in the IC tag attached to the mechanical element, so that when check is made to the database, the type of material, the lot control information, various history data and others, all associated with the mechanical elements can be ascertained. However, it may often occur that with those information on the mechanical elements, a cause of a trouble occurring in some of the mechanical elements cannot be clarified. By way of example, the difference in quality may arise even due to the difference in processing conditions at each of the process steps, and such difference in processing condition cannot be recognized from a result of examination.
The constant velocity universal joint is made up of a plurality of elements such as an outer race or outer coupling member, an inner race or inner coupling member, rolling elements and a retainer. No traceability is available to identify the difference in quality of the individual element while the examination result of the constant velocity universal joint after assembled is obtained. Since in the constant velocity universal joint, even the slight difference in material and precision brings about a substantial difference in performance, the hitherto suggested example of the quality control method utilizing the IC tags is incapable of resolving the problem.
Also, in the case of the control of the process steps, the conventional control method, in which for each process step, records are manually written in a book and/or inputted in a terminal, requires a substantial amount of labor and, therefore, it is indeed difficult to record a large amount of information in detail meticulously. In particular, when it comes to mechanical products, for example, constant velocity universal joints, each of which is made up of a plurality of elements produced in lots in all stages of the manufacturing process including a step of material purchase, a grinding step, a forging step and then a heat treatment step, the control of each element in each step of the manufacturing process is complicated and a substantial amount of labor is required in accomplishing manual recording of the information and inputting operation. Because of this, it is difficult to meet with the demands for the detailed history information on the mechanical products and, also, the control requires a substantial amount of cost.
In view of the foregoing, the application of the IC tags to the constant velocity universal joint has been contemplated, but the control method such as used in connection with automotive vehicles cannot be applied to the constant velocity universal joints. In the case of the example suggested in the previously mentioned patent document (the Japanese Laid-open Patent Publication No. 2002-169858), the IC tag is attached to an automotive vehicle itself, which is an object to be controlled, and information on each of various manufacturing steps is recorded in the IC tag. The IC tag is attached to a frame or the like. However, in the case of the constant velocity universal joint, since the constant velocity universal joint has no element, which provides a complete fiducial such as the frame or the like in the automotive vehicle and since in the manufacturing process each element is manufactured through, for example, the forging and heat treatment steps, it is difficult to secure the IC tag to the constant velocity universal joint. Also, in the constant velocity universal joint, since the outer race, the inner race, the retainer and so on are individually controlled after the manufacturing process including the step of material purchase, the forging step, the heat treatment step, the grinding step and so on, the application of the IC tag to the quality control poses a problem of how it should specifically be used and, therefore, the efficient application of the IC tag is difficult to achieve.